True, his breastbone (b,  Fig. 33) is deep and thin instead of flat, and those joints of his backbone which lie between his neck and tail are soldered firmly more like those of the tortoise, and he stands only upon two feet. Yet this last difference is merely apparent, for if you look at the bones of his wings you will find that they are, bone for bone, the same as those in the front legs of a lizard, only they have been drawn backwards and upwards so as to work in the air.

There is the upper arm (a ) answering to the same part of the lizard's front limb (p. 103); there is the elbow (c ); then the two bones of the fore-arm (fa ); then the wrist (w ), and a long hand (h ), which has lost almost all trace of separate fingers, except the little thumb (t ), which carries some feathers of its own, known as the "bastard" wing. Now when the sparrow is resting he draws back his elbow, folds his wrist joint, and brings the whole wing flat to his body. But when he wishes to fly he stretches his arms out and beats the air with them, and as his hand moves over most space, it is there that you will find the longest quill feathers, which stretch right to the tip of his wing; then next to these follow the feathers of his fore-arm, while those of the upper arm are short and close to his body, and over all these are the rows of covering feathers, which make the whole wing thick and compact.

Here, then, we have the lizard's front legs turned into a wonderful flying machine in the bird, and this in quite a different way  from the flying lizards which lived long ago, and which had only a piece of membrane to flit with, like bats. And now what has happened to the hind legs, the only ones used as legs by the birds? Look at the sparrow as he clasps the bough with his toes, and you will, perhaps, be puzzled why the first joint of his leg turns back like an elbow and not forward like a knee. Ah! but that joint is his ankle, and the knob behind is his heel (h ), for the bones of his foot have grown long and leg-like; and he always stands upon his toes, the rest of his foot forming a firm support to hold his body up in the air. Look at the skeleton and you will find his true knee (k ) up above; and if you go to the Zoological Gardens and watch the Adjutant birds, you will often find them resting their whole foot upon the ground (see Fig. 34), and comical as it looks, it will help to explain the curious foot and leg of a bird.

Already, then, we see that the bird is using the same bones as a reptile, though he uses them in a different way; and besides these resemblances between the skeletons of birds and reptiles there are two special ones easy enough for us to understand. We saw in the snakes and the lizards that they have a separate bone (9, Figs. 23 and 26) joining the lower jaw on to the head; now you will find this same bone in the sparrow and in all birds (see Fig. 33), but in quadrupeds this bone is not to be found, the part representing it being changed into one of the bones of the ear. Again, the sparrow's skull is joined to his backbone by a single half-moon-shaped knob, which fits into a groove in the first joint or vertebra. This also we find in reptiles, while all higher animals have two such knobs, so that although they can nod the head upon these, they cannot turn it upon them, and consequently the first joint turns with the skull upon the second vertebra.

These, then, are some of the reasons why Professor Huxley tells us that though frogs and reptiles look in many ways so like each other, yet in truth the frogs must be grouped with the gill-breathing' and fish-like animals; Ichthyopsida—ichthys,  fish; opsis,  appearance.") ?> while the cold-blooded reptiles, when we come to look closely into them, are linked with such different looking creatures as the bright and merry birds. Sattropsida—sauros,  lizard; opsis,  appearance.") ?> But we have also another and stronger reason for thinking that reptiles and b:rds are distant connections; for in those far bygone times (see p. 92), when the huge land-lizards browsed upon the trees, the birds living among them were much more like them in many ways than they are now. From their skeletons and feathers which we find, we know that the strange land birds which then perched on the trees had not a fan-shaped tail made of feathers, growing on one broad bone as our birds have now (p,  Fig. 33), but they had a long tail of many joints like lizards,  only that each joint carried a pair of feathers, and like lizards too they had teeth in their jaws,  which no living bird has. They must have been poor flyers at best, these earliest known birds, for their wings were small and the fingers of their hand were separate more like lizard's toes, two of them at least having claws upon them, while their long hanging tail must have been very awkward compared to the fan-shaped tail they now wear. For some time they were the only birds we know of, but later on we come upon the bones of water-birds telling the same story. For some about the size of small gulls, Ichthyornis,  fish-bird.") ?> though they flew with strong wings and had fan-shaped tails, still had teeth in their horny jaws, set in sockets like those of the crocodile, while their backbones had joints like those of fishes rather than birds; and with them were other and wingless birds Hesperornis.") ?> rather larger than our swans, but more like swimming fish-eating ostriches, for their breastbones were flat, not thin and sharp like the sparrow's, and they had scarcely any wings, short tails, long slender necks, and jaws full of teeth, this time set in grooves like those of lizards and snakes.

In these and many other points the early birds came very near to the reptiles—not to the flying ones, but to those which walked on the land. And now, perhaps, you will ask, did reptiles then turn into birds? No, since they were both living at the same time, and those reptiles which flew did so like bats, and not in any way like the birds which were their companions. To explain the facts we must go much farther back than this. If any one were to ask us whether the Australian colonists came from the white Americans or the Americans from the Australians, we should answer, " neither the one nor the other, and yet they are related, for both have sprung from the English race." In the same way, when we see how like the ancient birds and reptiles were to each other, so that it is very difficult to say which were bird-like reptiles and which were reptile-like birds, we can only conclude that they, too, once branched off from some older race which had that bone between the jaws, that single neck joint, and the other characters which birds and reptiles have in common.

But long ago they must have gone off each on their own road, the reptiles filling the world for a time, flying and walking and swimming, till they found at last that creeping was their most successful way of life; the birds on the other hand becoming more and more masters of the air and the water, so that, while keeping the same bones and parts as the reptiles, they have grown into quite different beings in their form and habits, giving up the long-jointed tail of the Archleopteryx,  or ancient-winged bird, for the compact feathered fan which helps to balance them in their flight, and the teeth of the water-birds for the sharp and horny beak, which, together with their claws, is their chief weapon of attack and defence now that they have employed their front limbs as wings.

Nor shall we have far to look for the secret of their success in life. Just as the reptiles have an advantage over the naked frogs and newts by having strong scaly coverings in their skin, so the birds have an advantage over the reptiles in that beautiful feathery plumage which covers their body, and the powerful muscles which work their limbs. For it is by means of these that they have been able to move quickly and travel far, and to develop that bright nervous intelligence which has grown more and more active as they have been carried into fresh scenes and experiences, overcoming new difficulties and enjoying new pleasures.

Remember for a moment how weak the lizard's limbs are, so that his body always drags upon the ground; and then look at the bird's tight grasp of the bough and the rod-like legs which raise his body above it. Watch him as he beats the air with his wings, rising and sinking, turning and swerving at will, and you will see that he has earned freedom, strength, and active life, by means of the strong muscles which move these legs and wings, and the feathers which provide him with an instrument for beating the air. Feel a sparrow's fat little breast, or see how much meat comes off the wing and breast of a pigeon, and then, if you consider that all this flesh is muscle used for moving his wings, you will not wonder at his easy flight. For the muscles of a bird's breast often weigh more than all his other muscles put together, and while one enormous mass of muscle in front of the breast works to pull down the wing, another smaller one, ending in a cord or tendon,  passing like a pulley over the top of a bone (c,  Fig. 33, p. 126), pulls it up, so that by using these, one after the other, the bird flies.

But where have the feathers come from,—those wonderful beautiful appendages, without which he could not fly? They are growths of the bird's skin, of the same nature as the scales of reptiles, or those on the bird's own feet and legs; and on some low birds such as the penguins they are so stiff and scale-like that it is often difficult to say where the scales end and the feathers begin. All feathers, even the most delicate, are made of horny matter, though it splits up into so many shreds as it grows that they look like the finest hair, and Dr. Gadow has reckoned that there must be fifty-four million branches and threads upon one good-sized eagle's feather.

When these feathers first begin to grow they are like little grooved pimples upon the flesh, then soon these pimples sink in till a kind of cup is formed all round them, and into this cup the soft layer just under the outer skin sends out fibres, which afterwards form the pith. Round these fibres rings of horny matter form, and then within these rings, in the grooves of the soft pimple, the true feather is fashioned. First the tips of the feathery barbs, then the shaft, and then the quill appear, as the feather grows from below, fed by an artery running up into the pimple; till at last, when the whole is full-grown, tile quill is drawn in at the base, and rests in its socket, complete.

Some of these feathers are weak and soft, with slender shafts and loose threads growing all round them, and these are the downy feathers which lie close to the body and keep the bird warm. Others, which cover the outside and form the wings and tail are flat, with strong quills and shafts, and a double set of barbs growing upon each shaft; and if you look at these wing feathers under a strong microscope you will see that they have a special arrangement for helping them to resist the air. For not only have all the little featherlets or barbs  rows of other featherlets or barbules  growing upon them, but these again are covered with fine horny threads, often hooked at the tip, which cling to the next barb, so that the feather is woven together as it were, in a close web, and if you strike it against the air you will find that it resists it strongly.

Now in a bird's wing the feathers are so arranged that they lap one under the other from the outside of the wing to the body, so that when the bird strikes downwards they are firmly pressed together, and the whole wing, which is hollow like the bowl of a spoon, encloses a wingful of air, and as this is forced out behind, where the tips of the feathers are yielding and elastic, he is driven upwards and forwards. When, however, he lifts his wing again, the feathers turn edgeways and are separated, so that the air passes through them, and he still rises while preparing for the next stroke. All this goes on so rapidly that even the heron makes 300 strokes in a minute, and the wild duck Soo, while in most birds they are so rapid that it is impossible to count them; yet all the while the little creature can direct his flight where he will, can pause and direct his wings to the breeze so as to soar, can swoop or hover, wheel or strike, guiding himself by the outspread tail and a thousand delicate turns of the wing.

All this complicated machinery, however, would not have served the bird much if his body had been as heavy, and his blood as cold, as those of the lizard and the crocodile. But here he has made a great step forward. In the first place, he has a heart with Four chambers, two on the right side and two on the left; and while one of those on the right side receives the worn-out blood from the body and pumps it to  the lungs to be refreshed, one of those on the left side receives it from  the lungs when it is refreshed, and the other pumps it into the arteries to feed the body. So here we see for the first time among our backboned animals a creature whose good and bad blood are never mixed in the heart (compare pp. 23 and 76), but it gets all the benefit possible from its breathing, and the blood is kept fresh and pure.

Moreover, a bird's lungs are large, and are continued into several large air-sacs, which in their turn open out into tubes which carry air actually into the bones,  many of which are hollow instead of containing marrow like those of other animals.

And now we begin to see how wonderfully these little creatures are fitted for flying. With all this air within them, not only is their blood kept hot by constant purifying, but their bodies are much lighter than if their bones were solid, and they can present a much broader surface to float upon the air without increasing equally in weight. Meanwhile, their feathery covering prevents the cold air around from chilling them, so that they are not only warm-blooded animals, but actually warmer-blooded even than ourselves.

Thus, then, Life has spread her feathered favourites over the world. For them there are no limits except the extreme depths of the water below, and the height beyond the atmosphere above. Wherever air-breathing creatures can go, there some bird may be found. On the dizzy ledges of inaccessible cliffs, on the wide boscm of the open ocean, on the sandy wastes of the desert, in the tops of the highest trees, on the cloud-capped peaks of the mountains, diving or swimming, flying or soaring, running, perching, darting, or sailing for miles and miles without one moment's rest, they find their way everywhere, and there is no spot from the icebound countries of the Arctic zone to the warm bright forests of the tropics where they do not penetrate; while their sharp eyes, kept free from dust and harm by a third eyelid moving rapidly sideways, see far into the distance, and thus as they soar into the sky they have a power, possessed by no other animals, of overlooking a wide domain. Nor have they been obliged, like the reptiles, to take up strangely different forms to suit their various habits, for so wonderfully does their body meet all their wants that very slight changes, such as a broad body and webbed feet for the swimmers, long bare legs for the waders, a long hind toe for grasping in the perchers, and sharp claws and beak for the birds of prey, fit each one for his work, and are some of the chief distinctions we can find between them.

Even the heavy running birds, the Ostriches of Africa, the Rheas of South America, and the Emus and Cassowaries of Australia, still remain truly bird-like, though their wings are unfit for flight. True, their breastbones are flat instead of keel-shaped, for they have no need of strong muscles to move their wings, which now serve only as sails to catch the wind as they run, and in many other ways they are an older type than our flying birds; but their wing bones are formed as if they were used for flying, and their feathers, though loose and downy because they have no little hooklets, are like those of other birds.

Strong powerful creatures they are, even in confinement. Yet how little can we picture to ourselves, when we see the Ostrich trotting round his paddock in the Zoological Gardens, with his wings outspread, what he is when he courses over the free desert!—

There the soft pads under the two toes  of each foot rebound from the yielding sand as his well-bent legs straighten with a jerk one after the other, making his body bound forward at full speed. Then he raises his wings, sometimes on one side, sometimes on both, to balance himself, and to serve as sails to help him; and with this help his stride is sometimes as great as twenty feet, and he dashes along at tilt rate of twenty-six miles an hour. He is not so heavy as he looks, for many of his bones arc hollow, his feathers are downy and soft, and his wing-bones are small; and it is to his featherless thighs that you must look for the strong muscles to which he trusts for all his speed, as with outstretched neck he bounds across the plain.

If we go back to long bygone times, before the lion, the leopard, and other ferocious animals found their way into Africa, we can imagine how this great running bird took possession of the land and became too heavy for flight; while as time rolled on, he gained that strength of body and leg which now is his great protection as he dashes along, his four or five wives following in his train. The ostriches can travel over wide distances from one oasis to another, feeding on seeds and fruit, beetles, locusts, and small animals, and fighting fiercely with legs and beak if attacked. And when the springtime comes the wives lay their eggs in a hole scooped in the sand, or often in some dry patch of ground surrounded by high grass, till sixteen or twenty are ready; and then they take their turn (the father among the rest) of sitting upon them, at least at night, even if they leave them to the heat of the sun by day. And when six weeks have passed the father grows impatient, and, pressing the large bare pad in front of his chest against each egg in turn, breaks it, pull out the membranous bag with the young bird in it shakes him out, and, swallowing the bag, goes on to another. In this way the whole downy brood are soon set free, and begin picking up small stones to prepare their gizzard or muscular second stomach for grinding, while their parents scrape the sand and find and break up food for them.

So the ostrich lives its life in Africa, from Algeria right down to Cape Colony; while its smaller and lighter-coloured relations, the Rheas, with their three-toed  feet, course over the plains of Paraguay and Brazil, on the other side of the Atlantic, often swimming from island to island, in the bays or across the rivers, but quite unable to fly with their soft hair-like feathers, though their wings are larger than those of the ostrich. Then when we turn to the East we find other running birds; the Cassowary, with its three toes, its horny helmet, its five long single feathers, and its five naked pointed quills in the place of a wing, feeding on fruit and vegetables in New Guinea, or sharing the dreary scrubs of Australia with the almost wingless Emus wandering in pairs, the only constant married couples among the running birds.

Nor is New Zealand left without a representative of this family, for there we have the curious little Apteryx or Kiwi (Fig. 36), with its thick stumpy legs, its long beak, and its soft downy body, under which are hidden its aborted wings. Perhaps it is because he is small and insignificant that the apteryx has lived on till now, crouching under the bushes by day and creeping about in the twilight, thrusting his long nose-tipped beak into the damp ground to draw out the worms. For long ago, though in the memory of man, as we learn from the traditions of the aories, other wingless birds called Moas, which were six or seven feet high, lived in New Zealand, and had fierce fights with the natives. We find their bones now, often charred from having been cooked in the native ovens, and when they are put together they give us skeletons which show that these birds must have been as formidable as that great bird of Madagascar, the Æpyornis, whose gigantic bones and eggs, three times the size of ostrich eggs, have been found, though the bird itself has never been seen.

But these are gone now, and their relations the Emus are fast following them; for however well these flightless birds may flourish on the broad plains and deserts, where only their wild companions are around them, they are sadly at the mercy of man. The proud eagle can fly far beyond the reach of the hunter's gun; the little lark, if she be only wary enough, may trill out her song in the blue vault above and leave the cruel destroyer far below; but the emu and the cassowary, the rhea and the ostrich, have lost the power to leave the earth; and if it were not that we prize the two last for their feathers, they, too, like their companions, might live to rue the day when they became runners instead of conquerors of the air.

It is very different, however, with the water-birds, for they have not only kept the power of flight, but have gained the double advantage of also floating safely on the water. Look' at our common wild duck. We might have taken him just as well as the sparrow for our type of a bird, and yet while the sparrow leads a land life in the trees, the duck's home is on the water, and many of his relations live cradled on the open ocean.

See his broad boat-like body which floats without any effort of his; notice how closely it is covered with short thickly-grown feathers, which protect him from the chilly water, while he keeps them well-oiled with his beak, from an oil-gland which all flying birds have at the base of the tail. Watch how he swims, drawing his webbed foot together as he brings it forward, and spreading it like a fan to strike the water as he drives it back. Then, as he feeds, watch him gobbling in the mud and then shaking his head as he throws his beak up in the air, For he, like all ducks and geese, has a set of thin horny plates inside his broad bill, and they sift the mud, while the tender tooth-like edges of his beak and tongue feel out the suitable morsels.

All this time he is a water animal, but when he rises and flies he is also master of the air, for his strong wings carry him stoutly, so that he can migrate from one pool to another; or in winter, when the pools are frozen, to the open sea. He is by no means the best flyer of his family, and yet he is spread over Europe and North America, and even as far east as Japan, while his ocean-loving cousin, the eider-duck, lines her nest and lays her eggs high up in Arctic latitudes, and dives and swims in the open ocean. So too his relations, the wild swans and geese which wander in the lakes and swamps of Lapland, Siberia, and Hudson's Bay, feeding on water-weeds, worms, and slugs, build their nests in the summer in the far north, and then fly thousands of miles southwards to their winter homes, their strong wings whirring in the air as they go.

Yet these are scarcely as true sea-birds as the divers, the Guillemots and Puffins, the Auks and Grebcs, which swim out all round our coasts, and dive deep down to feed on the fish below. How clumsy they are on land and how skilful in the water! You may see numbers of guillemots and puffins in summer on the high cliffs of the north of Scotland, or of Puffin Island in the Mcnai Straits; the guillemots laying their eggs on the bare ledges, and the puffins in holes which they burrow in the cliff's face; and they sit so doggedly upon their nests, and shuffle and hop along so awkwardly, that men climbing up, or let down by ropes from above, knock them over as they go. But wait till the eggs are hatched, and the little ones have broken out of their shelly prison, each one cracking his shell from inside by means of a little horny knob, which all baby birds have for this purpose at the end of their beak, and which falls off when they are fairly born. Then fathers, mothers, and young ones, able to take care of themselves as soon as hatched, launch out into the open sea in August, and there is a sight of diving and swimming and fishing grand to behold. The awkward legs, placed so far back on their body, now serve as powerful oars and rudders to drive their smooth satiny bodies through the water. Their thin narrow legs cut through the waves like knives, while their short stumpy wings, closely laid against their down-covered bodies, keep them from being chilled, and so do the air-bubbles which are entangled in their short thick feathers, and which give their backs the appearance of being covered with quicksilver when they dive after the fish below.

And then when the winter comes, those which have bred in the north fly and swim southwards to our coasts, where they are joined by the true divers and grebes which have come from the rivers and estuaries, where they have made their nests on some reedy bank or floating upon the water, and lived till their young ones are strong. This is their seafaring time; and whether near the shore, or miles out at sea, they dive and swim and make the ocean their home till spring comes round again.

Still all their roving is done chiefly by swimming, and they leave it to the Gulls and Petrels, the Terns and the powerful Cormorants and Gannets, to fly hither and thither over the wide sea. These birds have indeed reached the climax of a seafaring life, with their powerful wings, their sharp and often hooked beaks, and their short legs. They, too, feed upon the water, coming up with a fish in their mouth, but they do not dive under and swim like the guillemots. On the contrary, flying is their forte; they swoop down, and scarcely have they gone a few feet under water than they are up again, skimming on the waves as they swallow their prey, which may be anything from dead floating creatures to living fish which have ventured too near the surface. Yet they swim well too, and though the common gulls rarely go more than twenty miles from the shore, they are quite at home on the open ocean, and there is no habitable part of the globe without them. Still more venturesome are the petrels:—

They are smaller and lighter than the common gulls, and are never so happy as when darting over the foam of an angry sea, while their more delicate relations, the Terns or sea-swallows, with their long pointed wings and forked tails, are taking shelter in the quiet bays.

Lastly, king among all sea-flying birds is the gigantic petrel, the Albatross. What a grand fellow he is when he is once on the wing, though he has some difficulty in starting. Flying onward, onward, without resting day or night, his pure white body near down to the water, his large head and short thick neck slightly bent, and his long, narrow, black wings, often measuring ten feet from tip to tip, widely outspread, he beats a few powerful strokes, and then sails along, using his head and tail as rudders to turn his wings to the wind. Often he will follow a ship for days, sailing round and round in circles, and yet keeping easily ahead, while all the time his bright eye watches the water to catch every chance of food. Jelly-fish, cuttic-fish, and real fish of all kinds, together with any dead creatures he may find afloat,—all is food to him, and his powerful beak will cut through the toughest morsel. For days and days he will fly on, never tiring, and feeding as he goes; and if he alights for a time upon the water he rises with difficulty, unless the waves are high and bear him up on their crests; and when he comes to rest it is on some island in mid-ocean, where he seeks a mate, and brings up his nestlings either on the low ground or on the top of a high mountain, in a hollow lined with grass and moss. Truly, if we look at the far-flying albatross we must acknowledge that the wings of a bird have given him the command of the sea as well as the land.

He forms a strange contrast to the curious stunted bird form which we may find in those same islands where the mother albatross lays her eggs. For there, in the islands of the South Pacific, close by the side of the albatross nest, are whole groups of strange-looking birds, the Penguins, with their fat, white, feathered breasts, their dark head and beak, their curious hind legs set right at the end of their body, and their small paddle-like wings, covered with short stiff feathers, quite useless for flight. We have come upon a strange story here, for our penguin is a low relation of the guillemots and puffins whom we left in the north, and, like the great northern auk, which has now been extinct for many years, he has lost the use of his wings. He has no dangerous enemies on these rocky inaccessible islands, where he and his companions form dense penguin rookeries upon the ground, unless it be the large gulls or skuas which steal the eggs. Nor has he any need for flying, for the sea is all around him, and even if he wishes to migrate to warmer waters in winter, he does so by swimming. Therefore we find that his wings are lost to him for any flying purpose, and nothing can be more awkward than he looks, shuffling or hopping along with outstretched arms, like a fat baby, till he comes to the water's edge. But when he dives in and swims it is quite a different matter. Then his easy wavy motion, like that of a seal, shows at once that his stumpy imperfect wings are excellent fins, while his feet serve him both as oars and rudders.

Thus we have traced our swimming and web-footed birds to their extreme types—the strongest flyer in the albatross, and the lowest, most fish-like bird in the penguin; while, if we were to follow the pointed-winged frigate-bird in his flight, or see the pouched pelican in his home, we should find another group of these web-footed birds, no longer merely standing upon rocks, but perching upon the boughs of trees, and building their nests by the side of rivers in warm countries nearly all over the world, or among the mangrove bushes of the tropical islands.

And now, if we return to our northern shores and pause upon the broad wet sands at low tide, we may chance to find whole flocks of active little birds hovering and running and wading in the water, or pecking on the sands; and the double-noted whistle of the Curlew, or the musical cry of the Peewit (or Lapwing), tell us at once that they are "waders,"—birds with bare legs, flat toes, and long beaks, which drop down on the muddy flats by the sea, seeking their food at the edge of the water. There they are, Curlews and Dunlins and Sandpipers, Plovers and Knots, Oystercatchers feeding on mussels and limpets, and Turnstones tilting up the lumps of mud to find food beneath. One and all they are running hither and thither, to seize here a shrimp or sand-hopper or a tiny fish, there a worm or a sea-slug; making the most of their time before the sea comes up and covers their feeding ground.

Here we have no webbed feet or legs set far back, but three long, flat, straight toes, well fitted for walking on marshy ground and treading lightly on water-plants, and slender bodies well balanced on long thin legs, which move so quickly as they run that you can scarcely see them; while, when they fly, their long wings carry them lightly through the air, with their legs stretched out behind.

What connection can there be between these active light little beings, and the broad-bodied web-footed swimmers? Go to the Zoological Gardens, and look at the Flamingo, with his long legs and curious curved beak. He is of the true swimming type, with his webbed feet and his sieve-like bill, with its rows of horny strainers like the geese; yet he feeds by wading in salt-water lakes and pools on the sea-shore, raking the bottom for food, and showing how a swimmer and a wader may once have had the same starting-point, before the one went out to sea, and the other in to shore. And then when we come back to our own little waders, and learn that they visit the sea, and feed upon the wet sands from the autumn to the spring, and then fly inland to build their nests in the damp meadows, feeding on earthworms, slugs, and insects of the land, we can see what an advantage this double life must be to them.

Notice, too, how shy and timid they have become from living among other animals, and watching for every danger. Try to get near one, and see how it will run on, turning its head hither and thither to watch, and at last will rise and be out of sight in no time. Or go and look for plover's eggs on the swampy grounds in our northern counties in the early summer, when

The mother will no sooner see you than she will crouch down, running along a rut, and then move slowly away with a drooping wing as if wounded, hoping to make you follow her and pass by the little earthy hollow where her precious eggs are lying. The experience of life has made these little ground-nesting birds very intelligent, since they have had a land as well as a watery home, and the little moor-hen, which, like the rails and crakes, has taken entirely to a freshwater life in ponds, brooks, canals, and rivers, has learned to hide her nest so skilfully, and to dive and swim so cleverly, that even a trained water-spaniel often loses her when close upon her home.

And as the swimmers have their large birds in the albatross, so the waders too have theirs in the Herons, the Storks, and the Cranes. Who does not know how the storks fly in flocks to the sunny south in winter, and come back in the spring to build their nests in the chimneys of the houses of Holland and Germany, feeding on the banks of rivers, and in the fens on lizards, fish, frogs, and water-snakes; or how the cranes pass their summer in the stormy north, and their winter among the old ruins of Egyptian greatness? But the herons remain with us all the year, feeding on shrimps and crabs on the weed-covered shores, or more often in ponds and lakes upon frogs, water-rats, and fish. How patiently you may see a heron stand with his head slightly bent, still and motionless, till a fish passes by! Then quick as a flash of lightning, his head darts forward, impaling or seizing the prey in the strong beak, and he is off to eat it at his leisure. Thus he lives a solitary life all the year until the spring-time, when he flies off to some group of lofty trees where for generations his family have built their nests, and, meeting with his fellows, piles up huge masses of sticks and grass among the tangled boughs.

And there the young herons are hatched and fed in the ancient heronry till they can perch and fly. For now among the waders we have come to birds that can perch, as we did among the swimmers (see p. 148). The heron has no longer the three-toed flat foot of the wader, with perhaps a slight spur behind, but a large fourth toe, with which he can grasp the bough; and as he flies across the country, uttering his strange harsh cry, often rising even higher than the hawks and falcons, and alighting on the top of some tall tree, few people would think of classing him among the waders, so like is he to those true land-birds whose life is spent in the air and whose home is in the trees.